By Adam Wise, MD and Samuel Lam, MD, RDMS
Chief Complaint: Abdominal pain
Image 1 Image 2 Image 3
1. What are the significant findings in the above ultrasound images?
2. Describe the ultrasound technique to assess for this condition.
3. Can emergency physicians reliably use point of care ultrasound (PoC US) to detect this condition?
Case Presentation: A previously healthy 7-year-old female presented with 1 day of intermittent abdominal pain associated with nausea. Her parents reported she was tolerating oral liquids, and denied any associated fever, vomiting, diarrhea, bloody stools, dysuria, urinary frequency, rash, cough, chest pain, or dyspnea. She was seen at her pediatrician’s office earlier that day and treated with ondansetron and ibuprofen. She was subsequently brought to the emergency department because of persistent and worsening pain.
On arrival she was in no acute distress and appeared well hydrated. Her vital signs were HR 100, BP 98/45, RR 20, SpO2 100%, T 37.0. Her abdomen was non-distended, with tenderness in the right upper and lower quadrants, without guarding or rebound tenderness. No masses were palpated. The remainder of her exam was unremarkable.
A PoC US was performed, and the above images were obtained. The radiologist on-call was notified of the findings. Ultrasound performed in the radiology suite confirmed the diagnosis of intussusception, which was successfully reduced with air enema.
Review of Intussusception
Intussusception is the most common cause of intestinal obstruction in patients between 3 months and 6 years of age, and is second only to appendicitis as the cause of a surgical abdomen in children. It is most frequent among children under 2 years old, with approximately 10%-25% of cases occurring after that age. Males are affected twice as often as females. It peaks in the spring and autumn, possibly related to preceding viral illnesses. 1
In children intussusception is almost always ileo-colic, where the distal ileum slides distally into the cecum, causing venous congestion and swelling, and later arterial compression, bowel necrosis, and perforation.1,2 In children, unlike adults, there is rarely an identifiable lead point.1-3 Only a minority of patients present with the classic triad of intermittent abdominal pain, abdominal mass, and bloody stools. Children are more likely to present with vomiting, often with intermittent crying, and may appear asymptomatic or nontoxic. For this reason, intussusception is commonly misdiagnosed as viral gastroenteritis.1,3
Since the early 1980s ultrasound has been the imaging modality of choice to detect pediatric intussusception. Treatment consists of pneumatic reduction with air, barium, or water enema. Irreducible cases, or cases associated with perforation or sepsis are treated surgically, sometimes requiring bowel resection. Early detection is associated with successful reduction by enema.
Image 4a Image 4b
Answers to questions
1. Images 1-3 are consistent with intussusception. The classic findings are the presence of a bull’s eye sign in the short axis view (Images 1 and 2), often in the right upper and lower quadrants. The “bull’s eye” appears to have a hypoechoic outer ring around a hyperechoic inner ring. This corresponds to concentric bowel loops with varying degrees of associated wall edema.1 In the long axis view, layers of hyperechoic bowel wall can be visualized in a “stacked” fashion (Image 3). The presence of free fluid may indicate perforation, and is associated with a higher risk of perforation with nonsurgical reduction attempts. 1
2. To assess for intussusception the examiner should perform a thorough graded compression exam of the entire course of the colon, starting in the right lower quadrant and progressing superiorly, moving from right upper quadrant to left upper quadrant horizontally, and then inferiorly to the left lower quadrant (Image 4a). Alternatively, a “lawnmower” approach may be used, using graded compression of the entire abdomen (Image 4b).
3. Several studies and case reports have demonstrated the usefulness of PoC US performed by emergency physicians for the diagnosis of intussusception. 2,6-8 Riera et al. found that with 1 hour of training emergency physician sonographers could reliably assess for intussusception, with a sensitivity of 85% and specificity of 97%.8 In 2014 Lam et al. found that PoC US trained emergency physicians detected intussusception with a sensitivity of 100% and a specificity of 94%.7 A study by Zerzan et al. reported similar test characteristics. 9
PoC ultrasound can be reliably used to diagnose pediatric intussusception among patients with abdominal pain or vomiting.